Mathies et al. (U.S. Patent Publication 2004-0209354, Oct. 21, 2004) describes a microfluidic structure comprising: a first surface including a pneumatic channel; a second surface including a fluidic channel; and an elastomer membrane located between the first and second surfaces such that the application of a pressure or a vacuum to the pneumatic channel causes the membrane to deflect to modulate a flow of a fluid in the fluidic channel. The patent further describes a method of bonding a glass wafer to a layer of PDMS by cleaning the wafer and PDMS membrane in a UV ozone cleaner prior to assembly. Fluid flow in a fluidic conduit of such devices can be regulated by a diaphragm valve in the conduit that comprises a valve seat on which the elastomer membrane sits. When in contact with the seat, the elastomer membrane blocks fluid flow across a fluidic conduit. When out of contact with the seat, a passage exists that allows fluid communication across the valve.
Mathies et al. (supra) indicates that the device can have surfaces of glass plastic or polymer. Anderson et al. (Nucleic Acids Res. 2000 Jun. 15; 28(12):E60) describes a plastic device held together using ultrasonic welding or adhesives. Samel (“Novel Microfluidic Devices Based On A Thermally Responsive PDMS Composite,” School of Electrical Engineering, Royal Institute of Technology, Stockholm. Sweden, Sep. 7, 2007) discusses selectively bonding PDMS to a substrate using an anti-stiction pattern. Jovanovich et al. (WO 2008/115626, Sep. 25, 2008) describes microfluidic chips made from plastic components. The document refers, among other things, to using transfer tape or other adhesives to bond plastic parts.